Cutter Blade for Mower

ABSTRACT

A cutter blade for a mower is driven to rotate about a vertical axis inside a housing. The cutter blade includes a blade body, a blade portion formed in the blade body and a wind generating portion formed in the blade body on its side opposite in a width direction thereof to the side where the blade portion is formed, the wind generating portion being formed by being raised and bent from the blade body over a predetermined area from an end in a longitudinal direction thereof. At an outer end portion of the wind generating portion in the longitudinal direction of the blade body, there is formed at least one recessed portion recessed more inwards than the remaining portion of the outer end portion.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No.2013-195794 filed Sep. 20, 2013, the disclosure of which is herebyincorporated in its entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a cutter blade for a mower which isdriven to rotate about a vertical axis inside a housing.

2. Description of the Related Art

The cutter blade described above generates a wind inside a housing by awind generating portion, so that this wind raises grass for facilitatingits cutting or conveying cut grass. Incidentally, by enlarging the windgenerating portion, it is possible to increase the amount of windgenerated for enhancement of the ability to raise grass or to covey cutgrass. On the other hand, with this type of cutter blade, a negativepressure can sometimes be generated on the back side of the windgenerating portion (on the rear side relative to the rotationaldirection of the cutter blade). And, generation of such negativepressure leads to generation of vortex at this negative pressureportion, which in turn tends to invite increase of noise.Conventionally, as an arrangement for preventing generation of anegative pressure on the back side of the wind generating portion, thereare known cutter blades disclosed in e.g. Japanese Unexamined PatentApplication Publication No. 2002-315418 and Japanese Unexamined PatentApplication Publication No. 2005-312396. More particularly, JapaneseUnexamined Patent Application Publication No. 2002-315418 and JapaneseUnexamined Patent Application Publication No. 2005-312396 disclosecutter blades wherein a hole portion is provided at the wind generatingportion for establishing communication between the front side of thiswind generating portion (the front side relative to the rotationaldirection of the cutter blade) and the back side of the same. With thesecutter blades, it is contemplated to enlarge the wind generating portionby allowing air communication from the front side to the back side ofthe wind generating portion via the hole portion formed in this windgenerating portion and to eliminate the noise associated with a negativepressure at the same time.

However, with the cutter blades disclosed in Japanese Unexamined PatentApplication Publication No. 2002-315418 and Japanese Unexamined PatentApplication Publication No. 2005-312396, the hole portion can sometimesbe clogged up with cut grass during use of the cutter blade. Withoccurrence of such clogging of the hole portion with cut grass, thecommunication of air from the front side to the back side of the windgenerating portion is hindered, so that negative pressure cannot beavoided sufficiently, thus failing to achieve the expected noiseprevention effect. In view of the above-described, there is a need for acutter blade capable of reducing noise with maintaining the windgeneration function by its wind generating portion.

Means for Achieving the Object

A cutter blade for a mower, according to the present invention,comprises:

a blade body;

a blade portion formed in the blade body; and

a wind generating portion formed in the blade body on its side oppositein a width direction thereof to the side where the blade portion isformed, the wind generating portion being formed by being raised andbent from the blade body over a predetermined area from an end in alongitudinal direction thereof;

wherein at an outer end portion of the wind generating portion in thelongitudinal direction of the blade body, there is formed at least onerecessed portion recessed more inwards than the remaining portion of theouter end portion.

With the above-described arrangement, an amount of air is supplied viathe recessed portion to the back side of the wind generating portion, sothat generation of a negative pressure can be prevented. Further, asthis recessed portion is open to the side of the outer end portion ofthe wind generating portion, it is also possible to prevent cloggingwith cut grass. For this reason, even when a grass cutting operation iscarried out continuously, air can be supplied to the back side of thewind generating portion, so that generation of negative pressure can beprevented continuously. Further, as the recessed portion is formed atthe outer end portion of the wind generating portion, this recessedportion is formed at the outer circumferential edge of the mower bladehaving the highest circumferential speed, thus tending to invitegeneration of a negative pressure. Therefore, it is possible to supplyair to the negative pressure portion in an effective manner. As aresult, even when a grass cutting operation is continued, noise can beprevented effectively. Thus, even when the wind generating portion isformed relatively large, noise prevention will still be possible.Accordingly, it is possible to reduce noise generation with maintainingthe wind generating function of the wind generating portion at the sametime.

In the above-described arrangement, preferably, the recessed portion isformed at a portion of the outer end portion excluding a boundary areafrom an upper end portion of the wind generating portion.

In the above-described arrangement, preferably, the recessed portion isnot formed at a boundary area in the upper end portion from the upperend portion of the wind generating portion. With this arrangement, therecessed portion is not existent at the boundary area of the windgenerating portion which portion is most distant from the rotationalcenter of the cutter blade. Therefore, it becomes possible to increasethe rotational circumferential speed of the wind generating portion, sothat its wind generating function can be maintained reliably.

In the above-described arrangement, preferably, a plurality of saidrecessed portions are provided; and the recessed portions and protrudingportions constituting areas between adjacent recessed portions arecontinuous with each other via a curved line as seen in a front view.With this, the recessed portions and the protruding portions are formedsmoothly continuous with each other via the curved line, so that stressconcentration at the recessed portions can be prevented and thedurability of the cutter blade can be enhanced.

In the above-described arrangement, preferably, as seen in the frontview, the recessed portion has a curved shape and a curvature of therecessed portion is set greater than a plate thickness of a plate memberforming the cutter blade. With this arrangement, the curvature of therecessed portion is made relatively large, thus facilitating formationof this recessed portion.

In the above-described arrangement, preferably, the recessed portion isformed at a position in the outer end portion corresponding to aboundary portion between the blade body and a raised portion of the windgenerating portion.

In the above-described arrangement, preferably, at the upper end portionof the wind generating portion, there is formed at least one recessedportion which is recessed more downward than the remaining portion ofthe upper end portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing an example of a riding type mower to which themower cutter blade of the present invention is applicable,

FIG. 2 is a partial vertical cross section of the mower,

FIG. 3 is a partial cross section of the mower,

FIG. 4 is a top plan view of the cutter blade,

FIG. 5 is a perspective view of the cutter blade,

FIG. 6 is an enlarged view showing a wing generating portion,

FIG. 7 is a view showing a cutter blade according to a furtherembodiment, and

FIG. 8 is a view showing a cutter blade according to a furtherembodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Next, embodiments of the present invention will be explained withreference to the accompanying drawings.

FIG. 1 is a whole side view showing a riding type mower 100 mounting amower M. As shown in this figure, this riding mower 100 includes atraveling vehicle body 20 supported on a pair of left and rightsteerable front wheels 1, 1 and a pair of left and right drivable rearwheels 2, 2. This traveling vehicle body 20 mounts a driver's seat 3 atwhich a rider is to be seated, a steering wheel 4 for steering the frontwheels 1, 1, etc. Further, at a front portion of the traveling vehiclebody 20, an engine 5 is mounted. Under this traveling vehicle body 20and between the front wheels 1, 1 and the rear wheels 2, 2, the mower Mis provided. The mower M is supported to be lifted up/down relative tothe traveling vehicle body 20 via a link mechanism 10. At a rear portionof the traveling vehicle body, a grass collector container 32 issupported.

As shown in FIG. 1 and FIG. 2, downwardly of the engine 5, there isprovided a power take-off shaft (PTO) shaft 43 for taking power off theengine 5. The output of the engine 5 is inputted to an input shaft 41via a transmission belt 42, and a driving power of the PTO shaft 43transmitted to the output end of the input shaft 41 is transmitted to acutter blade driving mechanism 22 for the mower M via a rotational shaft46.

The link mechanism 10 includes a pair of left and right front pivotlinks 11, 11 supported vertically pivotally to the traveling vehiclebody 20, a pair of left and right rear pivot links 12, 12 supportedvertically pivotally to the traveling vehicle body 20, and a pair ofleft and right coupling links 13, 13. A lift cylinder 15 is operablycoupled to one of the pair of the left and right front pivot links 11,11. In association with expansion/contraction of the lift cylinder 11,the pivot link 11 is pivotally operated. As a result, the mower M islifted up/down between a lowered working state in whichground-contacting gauge wheels 25 supported to front and rear sides ofthe mower housing 21 are placed in contact with the ground surface and araised non-working state in which the respective ground-contacting gaugewheels 35 are lifted off the ground surface.

Next, an explanation of the mower W will be given with reference to thedrawings.

As shown in FIG. 2 and FIG. 3, the mower housing 21 includes a pair ofmowing chambers 28, 28 formed side by side in the right/left lateraldirection inside the mower housing 21 by a top plate 21 a and sideplates 21 b formed continuously from the peripheral edge of this toplate 21 a and a cut-grass discharge opening 29 formed by providing acutout hole in the top plate 21 a.

The pair of mowing chambers 28, 28 are open to the ground surface on theside of the lower end of the mower housing 21 and are disposed adjacentand communicated to each other at a position located at the center inthe lateral width direction of the mower housing 21. The cut-grassdischarge opening 29 is located at a position upwardly of the portionwhere the pair of mowing chambers 28, 28 are adjacent to each other andis communicated to each cutting mowing chamber 28.

Two cutter blades 26, 26 are provided, with one of them being disposedin each mowing chamber 28. The cutter blade 26 is supported to arotational support shaft 26 a to be rotatable therewith, the rotationalsupport shaft 26 a extending through the top plate 21 a of the mowerhousing 21 and the cutter blade 26 is driven by a cutter blade drivingmechanism 22 to be rotated about a vertical axis provided in therotational support shaft 26 a. And, the cutter blade driving mechanism22 transmits a driving force of an input shaft 22 a operably coupled tothe rotational shaft 46, with using a bevel gear 22 b and a spur gear 22c.

A cut-grass discharge duct 27 includes duct lower structures 50 formedby adding metal plates to opposed lateral sides of the cut-grassdischarge opening 29 in the mower housing 21 and duct upper structures52 having coupling portions 52 a continuously connected to a pair ofleft and right support portions 21 c, 21 c provided at the front endportion of the mower housing 21 via pivot pins 51. The pair of left andright duct lower structures 50, 50 include a rear guide plate 53connected to and between lower portions of the rear ends of these ductlower structures 50, 50.

Regarding the cut-grass discharge duct 27, the lower portion of the sideplate on the left or right side of this cut-grass discharge duct 27 isformed by the pair of left and lower duct lower structures 50, 50, andthe duct upper structures 52 of the left and right side plates of thecut-grass discharge duct 27 and the top plate 52 b, and in operation, anamount of cut grass is conveyed in the form of a flow by the duct lowerstructures 50 and the duct upper structures 52 toward the rear upperside of the mower housing 21 to be fed to a conveyer duct 6.

As shown in FIG. 4 and FIG. 5, the cutter blade 26 is formed by punchinge.g. a steel plate. A blade body 70 of the cutter blade 26 includes,along its longitudinal direction, a first portion 71 where a holeportion 80 at which the rotational shaft 8 is mounted is provided,second portions 72 each forming a blade portion 81 and a wind generatingportion 82 and third portions 73 between the first portion 71 and thecorresponding second portion 72. The height position of the firstportion 71 is set higher than the height position of the second portion72 and the third portion 73 is inclined to extend progressivelydownwards from the first portion 71 toward the second portion 72.

As shown in FIG. 4 and FIG. 5, at each second portion 72, the bladeportion 81 and the wind generating portion 82 are formed. The bladeportion 81 and the wind generating portion 82 are formed along adiagonal line in each second portion. With this, the blade portion 81 isdisposed on the front side and the wind generating portion 82 isdisposed on the rear side relative to the rotational direction.

As shown in FIG. 4 and FIG. 5, a portion of the second portion 71 of theblade body 70 is bent to extend upwards, thus forming the windgenerating portion 82. The wind generating portion 82 includes an outerend portion 82 a which is the outer end area of the wind generatingportion 82 relative to the longitudinal direction of the blade body, aninner end portion 83 c which is the inner end area of the same, and anupper end portion 82 b joining the upper end of the outer end portion 82a and the upper end of the inner end portion 82 c.

As shown in FIG. 4 and FIG. 5, at the outer end portion 82 a of the windgenerating portion 82, there is formed at least one recessed portion 90which is recessed more inwards than the remaining portion of this outerend portion 82 a. In the instant embodiment, three such recessedportions 90 are formed. Further, in this embodiment, at the upper endportion 82 b of the wind generating portion 82 a too, one recessedportion 90 is formed. That is, between and across the outer end portion82 a and the upper end portion 82 b of the wind generating portion 82,the recessed portion 90 and a protruding portion 91 located betweenadjacent recessed portions 90 are disposed in alternation. Namely, thiscutter blade 26, as shown in FIG. 6, has a shape formed by cutting awayportions corresponding to the recessed portions 90 (shaded portions inthe figure) from the wind generating portion 26 of the conventionalcutter blade 26. The shape of this recessed portion 90 is notparticularly limited, but this is provided by a cutting work forinstance. Needless to say, the recessed portions 90 can be formed by anyother work than the cutting work. For instance, at the time of punchinga steel plate for instance, the recessed portions 90 too can be cut awayat the same time.

In the instant embodiment, at the boundary area between the outer endportion 82 a and the upper end portion 82 b, a protruding portion 91 isdisposed (that is, no recessed portion 90 is formed here). Further, inthe instant embodiment, at the inner end portion 82 c of the windgenerating portion 82 too, no recessed portion 90 is formed. In thisembodiment, each recessed portion 90 and the protruding portion 91adjacent thereto are formed continuous with each other along a smoothcurved face (a smooth curve line as seen in its front view).

In the instant embodiment, the curvature of the recessed portion 90 isset either substantially equal to or greater than the plate thickness ofthe steel plate forming the cutter blade 26. Though not particularlylimited, in case the plate thickness of the steel plate ranges from 4.5mm to 6.0 mm approximately, the curvature of the recessed portion 90 canbe set to range from 4.5 mm to 12.0 mm approximately, preferably from6.0 to 12.0 mm approximately, more preferably from 9.0 to 11.0 mmapproximately. Further, the curvature of the protruding portion 91 toois set either substantially equal to or greater than the plate thicknessof the steel plate forming the cutter blade 26. Though not particularlylimited, the curvature of the protruding portion 91 too can be set torange from 4.5 mm to 12.0 mm approximately, preferably from 6.0 to 12.0mm approximately, more preferably from 9.0 to 11.0 mm approximately.Incidentally, the curvature of the recessed portion 90 and the curvatureof the protruding portion 91 can be made same or different.

When the traveling vehicle body 20 is caused to travel with setting themower M to the lowered working state, each cutter blade 26 inside themower housing 26 is driven to rotate about the vertical axis by thecutter blade driving mechanism 22, so that each cutter blade 26 effectsa grass mowing or cutting operation. The cut grass is conveyed by a windgenerated by the wind generating portion 82 in association with therotation of the cutter blade 26 and discharged via the cut grassdischarge duct 27 disposed at the upper position in the mower housing 21to the rear upper side of the vehicle body and collected in the grasscollector container 32.

In the course of the above, there is generated an air current via therecessed portions 90 from the front side of the wind generating portion82 (the front side face relative to the rotational direction of thecutter blade 26) to the back side face of the same (the rear side facerelative to the rotational direction of the cutter blade 26). Thus,generation of a negative pressure on the back side of the windgenerating portion 82 is avoided. Therefore, at the time of rotation ofthe cutter blade 26, generation of noise due to disturbance of aircurrent on the back side of the wind generating portion 82 can beprevented effectively.

Further, since the recessed portions 90 are open to the outer end sideof the wind generating portion 82, clogging of cut grass will occur lesslikely than the conventional arrangement of providing a hole portion inthe wind generating portion 82. Therefore, even when a grass mowingoperation is effected continuously, an amount of air can be supplied tothe back side of the wind generating portion 82, so that generation ofnoise can be prevented continuously. In particular, as the recessedportions 90 are formed on the outer end side of the wind generatingportion 82, these recessed portions 90 are formed at the outercircumferential edge of the cutter blade 26 where the circumferentialspeed is highest and negative pressure tends to occur most likely. Forthis reason, air can be supplied to the negative pressure portion in aneffective manner.

Further, as the recessed portion 90 has the shape of being opened on theouter end side of the wind generating portion 82, compared with the caseof forming a hole portion in this wind generating portion 82, thepossibility of the wind generating portion 82 being damaged at the timeof its formation is lower. Therefore, the recessed portions 90 can beformed easily. Incidentally, as described above, although it ispreferred that the recessed portions 90 and the protruding portions 91have curved shapes, the invention is not limited thereto, and theseportions have have other shapes such as a rectangular shape, etc.

OTHER EMBODIMENTS

(1) In the foregoing embodiment, there was explained the example inwhich three recessed portions 90 are provided in the outer end portion82 a. However, it will suffice if at least one recessed portion 90 isprovided in the outer end portion 82 a. That is, as shown in FIG. 7, thearrangement can be such that one recessed portion 90 is provided in theouter end portion 82 a. Further, it is also possible to provide two orfour or more recessed portions 90 in the outer end portion 82 b.Further, the recessed portion 90 in the outer end portion 82 b is notessential and can be omitted. Further, the recessed portion 90 can beformed in the inner end portion 82 c, too.

(2) In the foregoing embodiment, there was explained the example inwhich the recessed portions 90 are provided at same height positions ofthe pair of wind generating portions 82. Instead, as shown in FIG. 8 forinstance, the height positions forming the recessed portions 90 in thepair of wind generating portions 82 can be made different from eachother. In the case of the example shown in FIG. 8, at the heightposition where the recessed portion 90 is formed in one wind generatingportion 82, the protruding portion 91 is formed in the other windgenerating portion 82. With making the height positions forming therecessed portions 90 different from each other, even if an amount cutgrass is accumulated at the position corresponding to the recessedportion 90 in one wind generating portion 82, this accumulated cut grasscan be removed by the protruding portion 91 of the other wind generatingportion 82.

(3) In the foregoing embodiment, there was explained an example of themower M of rear discharge type having two cutter blades 26. However, thepresent invention is not limited to this foregoing embodiment. Theinvention may be applied to other types of mower M than the above, suchas a mower M having three cutter blades 26, a mower M having one cutterblade 26, etc. Further, the invention may be applied not only to suchrear discharge type mower, but also to a side discharge type mower M, amulching type mower M, or any other mower than the one described above.

(4) In the foregoing embodiment, the invention was explained by way ofthe example of the mid-mount type riding mower. However, the inventionis not limited to this foregoing embodiment. The invention may beapplied also to other types of mowers such as front mount type ridingmower, etc.

1. A cutter blade for a mower which is driven to rotate about a verticalaxis inside a housing, the cutter blade comprising: a blade body; ablade portion formed in the blade body; and a wind generating portionformed in the blade body on its side opposite in a width directionthereof to the side where the blade portion is formed, the windgenerating portion being formed by being raised and bent from the bladebody over a predetermined area from an end in a longitudinal directionthereof; wherein at an outer end portion of the wind generating portionin the longitudinal direction of the blade body, there is formed atleast one recessed portion recessed more inwards than the remainingportion of the outer end portion.
 2. A cutter blade for a moweraccording to claim 1, wherein the recessed portion is formed at aportion of the outer end portion excluding a boundary area from an upperend portion of the wind generating portion.
 3. A cutter blade for amower according to claim 1, wherein the recessed portion is not formedat a boundary area in the upper end portion from the upper end portionof the wind generating portion.
 4. A cutter blade for a mower accordingto claim 1, wherein the cutter blade comprises a plurality of saidrecessed portions; and wherein the recessed portions and protrudingportions constituting areas between adjacent recessed portions arecontinuous with each other via a curved line as seen in a front view. 5.A cutter blade for a mower according to claim 1, wherein as seen in thefront view, the recessed portion has a curved shape and a curvature ofthe recessed portion is set greater than a plate thickness of a platemember forming the cutter blade.
 6. A cutter blade for a mower accordingto claim 1, wherein the recessed portion is formed at a position in theouter end portion corresponding to a boundary portion between the bladebody and a raised portion of the wind generating portion.
 7. A cutterblade for a mower according to claim 1, wherein at the upper end portionof the wind generating portion, there is formed at least one recessedportion which is recessed more downward than the remaining portion ofthe upper end portion.